Tokina AT-X 124 PRO DX AF 12-24mm f/4 is one of a handful of lenses currently manufactured by Tokina, a division of Japanese optical manufacturing giant THK, which recently gobbled Pentax. The lens is manufactured for Canon and Nikon mounts and is specifically designed for APS-C type cameras (all of Tokina's DX designated lenses have reduced imaging circle which will cause severe vignetting if such a lens is used on a full-frame body). The build quality of the lens is superb - lens barrel is built of advanced polycarbonate (hardened Alumite) with texturized finish that gives the lens sturdy look and feel (all of Tokina's PRO marked lenses sport similar high quality build that easily rivals that of Canon's L lenses). There's no wobbling whatsoever and Tokina's unique One-Touch focus clutch (the focus ring that needs to be snapped to enable/disable manual focusing) is very tight, preventing from accidentally switching the focusing mode. Both focus and zoom rings are rubberized and rotate smoothly. The lens sports true internal focusing mechanism, meaning that the lens cams do not extend during zooming.

The optical construction consists of 13 elements in 11 groups, including two aspherical glass elements that reduce aspherical aberration typically associated with wide-angle lenses and a single SD super low dispersion element that corrects for chromatic aberration. As mentioned above, the lens offers both AF as well as full-time manual focusing. The minimum focusing distance is 30cm (11.8in), the minimum aperture is f/22 and the maximum magnification of 1:8 at 24mm. The lens is quite compact and light for an ultra wide zoom, measuring 84x89.5mm (3.3x3.5in) and weighing 570g (20.1oz). The front element of the lens does nor rotate, which allows attaching a circular polarizer to the front threat. The filter size is 77mm.

The lens is currently priced around US$450 (as of June 2007), undercutting Canon's EF-S 10-22mm f/3.5-4.5 USM and matching Sigma's AF 10-20mm f/4-5.6 EX DC HSM, which are it's primary competitor on the market. On APS-C type cameras with 1.6x crop factor, the field of view of the lens is equivalent to that of a 18-36mm lens on a 35mm camera. The factory box includes Tokina AT-X 124 PRO DX AF 12-24mm f/4 lens, BH-777 lens hood, manual and registration card.

Summary

Lens Composition

13 elements in 11 groups

Angular Field

122-84 degrees

Minimum Focus

30cm/11.8"

Focusing Action

AF/MF, ultrasonic

f-stop Scale

f/4-f/22, camera-controlled

Filter Size

77mm

Lens Hood

BH-777 (included)

Weight

570g/20.1oz

Dimensions

84x89.5mm/3.3x3.5"

Lens Case

Fitted case (optional)

Field Tests

The lens felt quite sturdy and thanks to the rubberized focus/zoom rings and texturized barrel, comfortable and easy to handle. The only issue I discovered with the lens was with the One-Touch Focus clutch which was a little bit unwieldy to handle, at least compared to a regular AM/FM switch found on most lenses. I actually needed to hold the camera firmly in one hand while pulling the focus ring up or down to switch from AF to MF. Doing that while trying to focus through a viewfinder is going to be problematic. Is it going to be a big problem? Unlikely, since how often do you expect an average photographer switching from manual to auto focus and back during a single photo session?

The lens showed some noticeable vignetting at 12mm with wide open aperture, which could get even worse if you are using a thick (>5mm) filter. Once stopped down to f/8, vignetting becomes pretty minimal. In the 18mm to 24mm range, vignetting is minimal even with stopped down aperture. The lens also showed moderate amount of distortion at 12mm, which is reduced towards the long end of the zoom range. While disappointing, this is expected from a lens with such a wide angle.

Images taken with the lens were pretty sharp in the center (throughout the zoom range) and somewhat softer around borders, with corner distortion clearly affecting sharpness. Overall however, the image quality remained consistent throughout the zoom range and the lens did not exhibit any glaring problems beyond the typically expected ones.

ISO 100, 1/640, f/5.6, 12mm

Lab Tests

Tokina AT-X 124 PRO DX AF 12-24mm f/4 (quite a mouthful) has showed some of the best results among ultra wide zoom lenses I have tested to date. The lens showcased best results at 12mm, where it was tack sharp both in the center and around borders. Performance here was actually on par with some of the best fixed focal lenses, which by itself is a huge surprise. Image sharpness degrades somewhat towards longer zoom range and this becomes especially noticeable around borders at f/4 (stopping down improves sharpness a little bit). At its peak (12mm focal length), the lens can deliver outstanding 19in and decent 24in prints - impressive results for an UWA zoom lens! And at its weakest point (24mm), the lens would still give you good 16in and decent 19in prints. Conclusion? Tokina clearly has a winner on its hands - this lens would easily give a run for the money to pretty much any APS-C UWA zoom available on the market these days.

MTF50 (Line Width/Inch on the Print) @ 12mm

Normalized raw MTF50 @ 12mm

MTF50 (Line Width/Inch on the Print) @ 18mm

Normalized raw MTF50 @ 18mm

MTF50 (Line Width/Inch on the Print) @ 24mm

MTF50 (Line Width/Inch on the Print) @ 24mm

Chromatic aberration was somewhat on the higher end and was especially pronounced around the edges (pretty much throughout the zoom range). f/4 fared worst: CA here was reaching 2px, but the rest of the tested aperture settings did not do much better - CA never really dipped below 1px even with stopped down apertures.

Image borders @ 12mm (100% crop): f/4 vs f/8

Alternatives

There are a few interesting alternative ultra wide zoom lenses available on the market. If you want to stick with a lens designed for APS-C type cameras, take a look at Canon EF-S 10-22mm f/3.5-4.5 USM (review), which demonstrates solid performance but also exhibits some noticeable artifacts (distortion and vignetting). Sigma AF 10-20mm f/4-5.6 EX DC HSM (review) is another worthy alternative, which would rival both Canon and Tokina in image and build quality. Finally, if you prefer to invest in a traditional EF mount lens, then Canon EF 17-40mm f/4L USM (review) should probably remain on your short list of UWA lenses to consider, and if you're willing to invest a small fortune in a high quality fast ultra wide zoom lens, then take a look at Canon EF 16-35mm f/2.8L II USM.

Recommendation

If you shoot with an APS-C camera, Tokina AT-X PRO DX AF 12-24mm f/4 is a lens to consider when shopping for an ultra wide zoom (you're out of luck if you're using a full-frame body). The build quality of the lens is superb, image quality can be easily considered to be among the best and some artifacts such as vignetting, CA and distortion that the lens exhibits, should not spoil the party in my opinion, since these types of artifacts are pretty common in majority of UWA lenses (besides, vignetting and CA can be easily corrected during post-processing). And considering Tokina's aggressive pricing, the lens should compare quite favorably against the de-factor leader of the pack, Canon EF-S 10-22mm f/3.5-4.5 USM.